(a) Field of the Invention
The present invention relates to a parallax barrier LCD, and more particularly, to a system for controlling brightness flicker of a parallax barrier LCD having a wide viewing angle that is capable of minimizing the brightness flicker by adjusting a permittivity curve depending on different times into a predetermined waveform when split barriers are on/off by movement of a viewer's viewing angle, and a method thereof.
(b) Description of the Related Art
Various methods for a technology relating to a stereoscopic display using binocular disparity are being proposed. One of representative methods allows a viewer to acquire a cubic effect by installing a lenticular lens or a parallax barrier spaced by a predetermine distance on a 2D image panel to cause different image information to be transmitted to a viewer's left and right eyes.
In the stereoscopic display technology using the lenticular lens, left and right images are arranged on a focus surface of a lens called a semi-cylindrical lenticular screen in a stripe pattern, and the left and right images are split depending on the directionality of a lens plate through the lens to allow the viewer to view a stereoscopic image without glasses.
The width of one lens is determined by a pixel width of a display device. Two pixels respectively corresponding to the left and right eyes are provided to allow a pixel at the left side of the lens to be viewed by only a right eye and a pixel at the right side of the lens to be viewed by only a left eye, thereby splitting the left and right images.
In the stereoscopic display technology using the parallax barrier, thin stripe vertical slits for transmitting or shielding light are arranged between a viewer's eye and an image at a regular interval and left and right images are alternately disposed at the front or back of the slits by an appropriate interval, and as a result, the left and right images are optically split when the image is viewed through the slit at a predetermined location, causing the viewer to acquire the cubic effect. That is, a stripe parallax barrier optical plate serving as special glasses is installed in front of a monitor screen to allow the viewer to recognize the stereoscopic image without wearing the glasses.
As such, the stereoscopic display technology adopts the method using the binocular disparity.
FIG. 1 is a diagram showing a concept of a known stereoscopic display, which is disclosed in U.S. Pat. No. 6,108,029.
As shown in the figure, the stereoscopic display is configured by installing a parallax barrier 12 in the rear of an image display panel 11 by a predetermined distance. In the image display panel 11, a left image L and a right image R are alternately arranged with a pixel pitch P, and in the parallax barrier 12, a transparent part 12a and an opaque part 12b are alternately arranged with a barrier pitch q.
Light emitted from a light source (not shown) passes through the transparent part 12a of the parallax barrier 12 and reaches both eyes RE and LE of a viewer through the image display panel 11. At this time, light that passes through the right image R of the image display panel 11 reaches the right eye RE of the viewer and light that passes though the left image L of the image display panel 11 reaches the left eye LE of the viewer.
The left image L and the right image R of the image display panel 11 are inputted into the left and right eyes RE and LE of the viewer as different 2D image information to allow the viewer to acquire image information having a cubic effect.
In FIG. 1, the parallax barrier 12 is installed in the rear of the image display panel 11, but the image display panel 11 may be installed in the rear of the parallax barrier 12.
If the entire opaque part 12b of the parallax barrier 12 is transparent, the light emitted from the light source evenly passes through the parallax barrier 12 and the image display panel 11 and reach the viewer. Therefore, a 2D planar image is displayed like the known 2D display. That is, the stereoscopic display may display both the planar image and the stereoscopic image by adjusting the opaque part of the parallax barrier 12.
The stereoscopic display needs a condition for the viewer to effectively perceive the cubic effect, and a relationship expression thereof is shown in Equation 1.d(2n+1)P(D+d)/S,q2P(D+d)/D d(2n+1)P(D+d)/S,q2P(D+d)/D  (Equation 1)
Herein, n represents a positive integer, S represents a distance between the left and right eyes of the viewer, D represents the shortest distance between the image display panel and the viewer's eye, d represents the shortest distance between the parallax barrier and the image display panel, q represents the barrier pitch of the parallax barrier, and P represents the pixel pitch of the image display panel.
FIG. 2 is diagram showing a parallax barrier applied to a known stereoscopic display.
The parallax barrier applied to the stereoscopic display includes a common electrode 21 of an upper plate or a lower plate, strip electrodes 22 of an opposite plate arranged at a regular interval of a barrier pitch q, and a power supply device 23 adjusting a transparent state and an opaque state by inducing rearrangement of a liquid crystal layer positioned between the common electrode 21 and the strip electrode 22 by supplying power to the common electrode 21 and the strip electrode 22.
When a voltage is applied between the common electrode 21 and the strip electrode 22 or the applied voltage is interrupted in the power supply device 23, a liquid crystal of the corresponding part becomes transparent or opaque to thereby display the stereoscopic or planar image.
FIGS. 3 and 4 are diagrams for describing disadvantages generated in a known stereoscopic display.
As shown in FIG. 3, the stereoscopic display allows the right eye RE of the viewer to view a right image R of an image display panel 31 and the left eye LE of the viewer to view a left image L of the image display panel 31 by actuating a parallax barrier 32. Therefore, the viewer acquires the cubic effect by synthesizing two images viewed to the right eye RE and the left eye LE in the brain of the viewer.
However, as shown in FIG. 4, when a viewing angle of the viewer deviates from a predetermined location, a part of an image is covered by the barrier, and as a result, the stereoscopic image is not implemented. For example, when the viewing angle of the viewer moves from locations of RE and LE to locations of RE′ and LE′, a part of the image is covered by the parallax barrier 32, and as a result, the parallax barrier 32 should be moved by W in order to maintain a stable stereoscopic image.
However, since the parallax barrier applied to the known stereoscopic display is fixed, a left-right viewing angle of the viewer is within approximately 5 degrees and is very limitative.
As a method for solving the known problem, as disclosed in Korean Unexamined Publication No. 10-2007-0023849, which is the prior art of the applicant, a split barrier scheme in which a barrier electrode for actuating the parallax barrier is split into a plurality of fine electrodes by using a fine pattern technology, and a driven part and a non-driven part are adjusted through appropriate combination driving as the viewing angle of the viewer moves to thereby vary locations of a transparent part and an opaque part of the parallax barrier, has been proposed.
FIG. 5 is a diagram showing movement of a barrier by a change of a viewing angle of a viewer in a stereoscopic display adopting a known split barrier scheme. The barrier is moved by appropriately combining and driving 8 split fine electrodes depending on the viewing angle of the viewer.
As shown in the figure, when the viewing angle of the viewer moves to the right side or the left side, the parallax barrier is moved by actuating the resulting split fine electrodes, thereby providing a stable stereoscopic image of which distortion is not generated at the moved viewing angle of the viewer.
However, in the known stereoscopic display adopting the split barrier scheme, a transmittance curve depending on different times is provided when the split barriers are on/off in order to move the parallax barrier as the viewing angle of the viewer moves, thereby causing brightness flicker.
FIG. 6 is a diagram showing an on/off relationship of split barriers depending on movement of a viewing angle of a viewer in a known stereoscopic display. In order to move the parallax barrier as the viewing angle of the viewer moves to the right side, an on/off operation of a bundle of 6 split barriers is as shown in FIG. 6.
At this time, a split barrier that is turned off and a split barrier that is turned on have different permittivity characteristics, and as a result, the brightness flicker occurs at a region where ON and OFF intersect each other as shown in “A” of FIG. 7.
Further, as shown in FIG. 8, in the known stereoscopic display adopting the split barrier scheme, the brightness flicker occurs due to moire of the viewing angle of the viewer.
As shown in the figure, even though all images viewed by the left eye LE and the right eye RE are implemented as a white image and the split barriers are fixed, due to the moire, the brightness flicker in which light is lightened and darkened occurs when the viewing angle of the viewer moves.
As described above, the brightness flicker that occurs due to the on/off operation of the split barriers or the moire of the viewing angle of the viewer offends the eyes of the viewer at the time when the viewer views the stereoscopic image, and as a result, the viewer can view a comfortable stereoscopic image only by solving the brightness flicker.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.